1. Field of the Invention
The present invention relates to a water treatment system, more particularly, to a water purification system.
2. Related Art
As modern people pay more attention to the quality of life, leisure activities are increasingly diversified, and currently, swimming pools and hot springs are common places for leisure activities. However, as people directly contact water, pollutants such as sweat, fat, cosmetics, and urine brought by swimmers during using, and dusts and leaves from outside make the water contaminated and turbid, and thus people have higher requirements on the safety and quality of the water. Therefore, organizations of swimming pools and hot springs must purify the water with different methods to ensure that the water quality meets the requirements of regulations. The common disinfection methods include chlorination disinfection, ozone disinfection, and UV disinfection.
Currently, chlorination disinfection is the most commonly used disinfection method, and chlorine was the dominant means for chlorination disinfection in the past, but now, sodium hypochlorite (commonly known as bleach) and chlorinated cyanuric acid (commonly known as solid chlorine, powder chlorine) are used instead due to the high risk of chlorine. The Business Sanitation Criteria issued by the Center for Disease Control, Department of Health, Executive Yuan expressly provides that free residual chlorine in the water of a swimming pool should be kept at 1-3 ppm, and the total bacterial count of Escherichia coli should be kept at a standard of lower than 1 CFU per 100 ml water. However, in addition to the function of sterilization, free residual chlorine can also oxidize organics and inorganics in the water due to high oxidation capability (−1.49V). Such oxidation process has two effects: one is the consumption of the free residual chlorine, and the other is the generation of combined chloramine products through the oxidation. Part of the combined chloramines is carcinogens, such as trihalomethanes (THMs), some of the combined chloramines may cause skin irritation, eye irritation, and respiratory discomfort, and so on. When the concentration of the combined chloramines is too high, the quality of the swimming pool water will be changed significantly, the concentration of free residual chlorine cannot be increased by using common amount of chlorine, and the quality of the water will be deteriorated and get turbid rapidly.
In order to address the problem of sterilization in water treatment, China Patent Publication No. CN2727152Y discloses a circulating treatment device for bathing water and swimming pool water, in which the water treatment includes filter processes of centrifugal sewage discharge, reverse osmosis, and active carbon filter, and finally UV sterilization is performed to finish the water treatment. China Patent Publication No. CN1702048A discloses a circulating physical-biological-chemical treatment system for (indoor) swimming pool water, which utilizes three treatment methods including physical (filter), chemical (sterilization), and biological (sewage treatment) to realize the purpose of water treatment.
However, the water treatment methods in prior art have disadvantages, for example, No. CN2727152Y patent is limited in the UV bactericidal efficiency and treatment capacity and cannot perform sterilization of water of large volume, and No. CN1702048A patent has the trouble that the residues will do harm to human body as chlorine dioxide is used in the sterilization.
In the field of household water purifier, there are many types of household water purifiers in the market, such as RO reverse osmosis, electrolysis, active carbon. According to the so-called reverse osmosis, a pressure greater than osmotic pressure is applied on the source water to generate a reverse osmosis effect, such that inorganic salts, heavy metals, organics, fungus, particles in the water cannot pass through the semipermeable membrane, and merely water molecules and smaller molecular salts can penetrate through the membrane and flow towards a side of pure water, while the pollutants will be condensed in the source water. According to the so-called electrolysis, a membrane or salt bridge is used during electrolysis of water to block the exchange of ions, such that the pH values of the water is changed, and at the same time, the oxidation reduction potential and the dissociation constant are changed, thus generating acidic water or basic water. Further, active carbon is a porous carbonaceous material having a porous structure, so it has a large surface area and has a very strong adsorption capacity. However, due to the fixed adsorption capacity, when the pores of the active carbon are saturated, the adsorption effect is reduced significantly. Therefore, the active carbon must be changed after being used for a period of time, otherwise, the pores of the active carbon will intercept the substances in the water, and bacteria will grow thereon, such that the active carbon becomes a breeding ground for the propagation of bacteria.
However, reverse osmosis will filter off mineral substances in the water completely, and long-term drinking of such water will cause some ions in the cells get out of the cells to balance the osmotic pressure due to the osmotic pressure inside and outside, and problems such as loss of calcium ions will occur, resulting in muscle weakness, and serious osteoporosis. Further, excessive wastewater is discharged during the reverse osmosis, thus causing waste of water resource. Additionally, the reverse osmosis cannot filter off bacteria and virus in the water effectively, thus the water after treatment cannot be drunk directly.
For the electrolysis water purification method, the water resource should be clean and free of contamination, otherwise, the electrolyzed water will be condensed water containing heavy metals. Due to the ion and anion, many heavy metals are condensed into a basic side, thus the condensed water containing heavy metals will be drunk.
Accordingly, the various household water purifiers mentioned above is inconvenient for users, because the purified water may not be suitable for drinking, and the filter material should be changed periodically.